I. Field of the Invention
The present invention is directed generally to a system for redistributing the axle loading of a multi-axle working vehicle of a class associated with transporting rather heavy loads which may not be uniformly carried by or distributed among the several axles of the vehicle. More particularly, the invention is directed to an improved tag axle system and a simple and efficient system for carrying and operating a tag axle between a deployed or ground engaging position and a stowed position. The improved tag axle system of the invention is lightweight and particularly versatile and adaptable to be accommodated by the tailgate structure or truck body structure of a front, side or rear-loading trash compacting refuse truck.
II. Related Art
Auxiliary load support devices deployable between a stowed and ground engaging or support position and commonly known as tandem axle, tag axle or auxiliary axle assemblies have been in use on various types of load-hauling work vehicles for some time. These include, in particular, dump trucks and refuse carrying trucks, or the like, which within a short time span may be driven in a heavily (fully) loaded, empty or in a partially loaded condition. The use of such downward deployable additional axle assemblies, of course, allows such vehicles when heavily loaded to deploy an optional, additional load supporting axle as needed so that the gross or total legal weight such vehicles can carry over the highways is increased at the same per-axle loading. Tag axle systems are generally designed so that they are in a deployed or ground-engaging and supporting posture only when the additional support is needed and are otherwise carried in a raised or stowed position to obviate the additional road friction and tire wear associated with the alternative of adding another permanent axle. Also, the use of a deployable system, in some cases, permits the placement of additional support where the addition or use of a permanent axle system would not be practical, such as, for example, in the case of additional tailgate support.
Devices of the described class designed to lend additional support to areas of vehicles, particularly refuse vehicles, include, for example, a system illustrated in U.S. Pat. No. 5,090,495 to Ronald E. Christenson, the inventor in the present application, and which is assigned to the same assignee as the present application. That reference describes a tag axle system including a pair of spaced stub axles having independently operated suspension systems each for lowering and raising the associated wheel.
While that system may be adapted to any multi-axle load hauling vehicle, it is particularly illustrated as supporting the tailgate of a rear-loading refuse truck having a rear refuse receiving hopper swept by an hydraulic compacting mechanism. The load of a rear-loading vehicle is particularly prone to a rearward directed imbalance because the loading trough area or tailgate hopper extends a considerable distance behind and beyond the normal rear axle and also drops down below the level of the frame of the truck to thereby produce an additional strain on the conventional rear truck axles. To eject packed refuse in such trucks, the entire rear tailgate must be raised and a rearward sweeping ejection mechanism utilized to discharge the refuse from a fully loaded truck at a landfill, or the like. A vehicle of the class is described and illustrated, for example, in U.S. Pat. No. 3,739,927 issued to Gollnick, which is deemed incorporated herein.
In the illustrative embodiment described in the above-referenced '495 patent, the tag axle systems are spaced behind the rear axle of the vehicle with the stub axles on either side of the tailgate of the vehicle. The tag axle assemblies are both carried by and deployable to directly support the tailgate itself and thereby assume part of the weight carried by the rear wheels of the vehicle. The tag axles also produce a leveraging effect to accomplish a forward directed redistribution of an additional portion of the large amount of weight carried by the rear wheels of the vehicle.
In the mounting and deployment system associated with the '495 patent, the tag axle support and deployment system mechanisms which operate to raise and lower the wheel assemblies include fluid operated devices which are preferably pneumatic springs rotatably attached to each end of an eccentric fulcrumed (unequal length leverage arms) lever system such that the inflation of the longer length lever arm pneumatic spring combined with the deflation or collapse of the pneumatic spring attached to the shorter leveraged arm results in the lowering or deployment of the tag axle, and the reverse, in the stowage thereof. The air-operated springs are mounted in a pivotal arrangement such that the ends of the springs are permitted to move and change relative angles in fluctuating between the inflated and collapsed state. While such embodiments have been found to be advantageous for certain applications, it has further been found, for example, that stationary mounting of the pneumatic springs eliminates additional moving parts and further assists in stabilizing the operation of the system. Also, supporting the pair of spaced tag axle assemblies from a common structural member has been found desirable. In addition, in accordance with the present invention, it has further been found possible to operate a tag axle assembly of the invention utilizing a single double-acting hydraulic cylinder for both deployment and retraction.
Accordingly, to improve and simplify the construction and operation of a pair of coordinated tag axles of load hauling vehicles, it is a primary object of the present invention to provide such an improved and simplified system.
Another object of the present invention is to provide an improved and simplified coordinated tag axle system that can be mounted on the tailgate or truck body of any style refuse vehicle.
A further object of the present invention is to provide a tag axle deployment assembly utilizing pneumatic springs of fixed mount.
A still further object of the invention is to provide a tag axle deployment and stowage assembly operated by a single, double-acting hydraulic cylinder.
A yet still further object of the invention is to provide a tag axle support and deployment system that uses separate deployment and stowage levers attached to a common stub axle mounting lever.
Other objects and advantages will occur to those skilled in the art through a familiarization with the specification, claims and drawings associated with the descriptions of the invention.